The 4 year old black male child in question is experiencing androgen action with no known androgen detected. He is virilized, with Tanner III genitalia and Tanner II pubic hair, but prepubertal size testes. His bone age is advanced 3.5 yrs and he is aggressive in his play activities. Baseline levels of testosterone,DHT, DHEAS, 17-OHP, and 11-desoxycortisol, as well as ACTH-stimulated levels of testosterone, 17-OHP, and 11-desoxycortisol are all within the normal prepubertal range. Urine evaluation of anabolic steroid was also negative.